The generation of electricity by the use of natural energy such as wind power and water power becomes popular instead of the generation of electricity by the use of the burning of coal, oil and so forth which is a factor of environmental warming and disruption. For example, a wind power electric generator making use of wind power is composed of a control unit for controlling the rotation of a windmill, an electric dynamo for generating power by converting the rotation force of the windmill into electrical energy and other necessary components, and serves to supply electric power for example for use in home by rotating the windmill and converting the rotation force thereof into electrical energy. This electric dynamo includes a rotator fixed to a rotatable shaft which rotates by the use of natural energy, a stator located opposite this rotator, and a housing to which the stator is fixed. An induction current is generated between the permanent magnet of the rotator and the magnetic pole of the stator core by the rotation of the rotatable shaft. However, there are a variety of problems in this type of electric generators.
It is a main object of the present invention to provide an electric generator with which cost reduction is possible by overcoming the various problems. The above object includes the cost reduction of the electric generator itself from the view point of the structure of the electric generator, and the cost reduction of the generation of electricity from the view point of the performance of the electric generator.
More specifically, the first object is to reduce costs by solving the difficulties in assembling an electric generator resulting from the centering required of the input shaft in the torque generating side relative to the output shaft to which the rotator is fixed. It is difficult to change the output shaft of an electric generator from its resting state to its rotating state due to the attractive force between the stator and the rotator and the inertial force of the rotator. Accordingly, there is a problem that the generation of electricity cannot be started with the output shaft being in its resting state, unless a large torque is available. In order to overcome such a problem, an electric generator has been developed in which a clutch is provided between the input shaft and the output shaft (for example, as described in Japanese Patent Published Application No. Hei 8-312523). However, in the case of the electric generator as described in the patent publication 1, there is a problem that the cost rises due to the so-called centering step, required during assembling, for aligning the input shaft of the input shaft in the torque generating side with the axis of the output shaft to which the rotator is fixed. Also, since the input shaft and the output shaft are separate parts, the cost furthermore rises.
The second object is to reduce costs by solving the difficulties in assembling an electric generator resulting from the heavy weight of the stator. The stator must be heavy because it is located opposed to the rotator. The larger the size of the stator, the heavier the weight. Furthermore, if the weight of the stator increases, it becomes difficult to wind coils inside of the cylindrical stator.
The third object is to improve the performance of an electric generator by solving the problem that the rotation of the rotatable shaft becomes unstable because of the use of natural energy, and thereby to achieve the cost reduction of the generation of electricity.
The fourth object is to improve the performance of an electric generator by solving the problem that the rotation of the windmill cannot be controlled due to a failure, and thereby to achieve the cost reduction of the generation of electricity. For example, there is proposed an electric generator provided with a sensor serving to detect an object which is entering in the vicinity of the electric generator and halt the rotation of the windmill to ensure the safety (as described in Japanese Patent Published Application No. Hei 2003-21046). However, in the case of such an electric generator, the windmill cannot be stopped when the electric generator itself breaks down due to the breakage of a parts resulting in the failure of the sensor operation and the like. Furthermore, since the rotation of the windmill cannot be controlled because of the failure, when the windmill swiftly rotates by a strong wind such as a typhoon, there is a danger that a parts of the windmill will be blown off.
The fifth object is to improve the performance of an electric generator by avoiding the decrease in the charging efficiency of a battery when the available natural energy is low (for example, in the case of a weak wind), and thereby to achieve the cost reduction of the generation of electricity. The wind power electric generator serves to convert the kinetic energy of wind power into an electric energy of electric power in the form of three phase alternating currents, and rectify the phase voltages as output from output lines with three phases to provide a charging voltage for charging a battery and an electric power source for various devices. However, during battery charging, the charging voltage undergoes a lot of changes due to the variation of wind power.
The present invention is invented taking into consideration the above circumstances. It is an object of the present invention to provide an electric generator for achieving the cost reduction of the electric generator itself from the view point of the structure of the electric generator, and the cost reduction of the generation of electricity from the view point of the performance of the electric generator, and a power supply equipment for use in this electric generator.